Semiconductor device with trench structures including a recombination structure and a fill structure

• US 8,921,931 B2
• Filed: 06/04/2012
• Issued: 12/30/2014
• Est. Priority Date: 06/04/2012
• Status: Active Grant

• Current Assignee: Infineon Technologies Austria Ag (Infineon Technologies AG)
• Original Assignee: Infineon Technologies Austria Ag (Infineon Technologies AG)
• Inventors: Mauder, Anton, Niedernostheide, Franz-Josef, Schulze, Hans-Joachim, Schulze, Holger
• Primary Examiner(s): Diallo, Mamadou
• Assistant Examiner(s): Chang, Jay C
• Application Number:
  US13/487,540
• Publication Number:
  US 20130320487A1
• Time in Patent Office: 939 Days
• Field of Search: 257/328, 257/331, 257/332, 257/333
• US Class Current: 257/331
• CPC Class Codes: H01L 21/761 PN junctions
• CPC Class Codes: H01L 21/76224 using trench refilling with dielectric materials trench filling with polycristalline silicon H01L21/763; together with vertical isolation, e.g. trench refilling in a SOI substrate H01L21/76264
• CPC Class Codes: H01L 29/0619 with a supplementary region doped oppositely to or in rectifying contact with the semiconductor containing or contacting region, e.g. guard rings with PN or Schottky junction
• CPC Class Codes: H01L 29/0649 Dielectric regions, e.g. SiO2 regions, air gaps
• CPC Class Codes: H01L 29/0692 Surface layout
• CPC Class Codes: H01L 29/861 Diodes
• CPC Class Codes: H01L 29/872 Schottky diodes

Abstract

A semiconductor body of a semiconductor device includes a doped layer of a first conductivity type and one or more doped zones of a second conductivity type. The one or more doped zones are formed between the doped layer and the first surface of a semiconductor body. Trench structures extend from one of the first and the second opposing surface into the semiconductor body. The trench structures are arranged between portions of the semiconductor body which are electrically connected to each other. The trench structures may be arranged for mitigating mechanical stress, locally controlling charge carrier mobility, locally controlling a charge carrier recombination rate and/or shaping buried diffusion zones.

Claims

1. A semiconductor device comprising:

a semiconductor body comprising;

a doped layer of a first conductivity type; and

a doped zone of a second conductivity type opposite to the first conductivity type, wherein the doped zone is formed between the doped layer and a first surface of the semiconductor body; and

trench structures extending from one of the first and a second opposing surface into the semiconductor body, the trench structures arranged between electrically connected portions of the semiconductor body, each trench structure comprising

a combination structure at the bottom of each of one or more of the trench structure, each of the recombination structures directly adjoining the doped zone and each recombination structure exhibiting a surface recombination rate of at least 10⁴ cm/s at an interface to the doped zone, and

a fill structure separating the recombination structure form the first surface at least in a direction perpendicular to the first surface, the fill structure being either (i) conductive and not concurrently electrically connected to both the recombination and any other conductive structure outside the trench structure, or (ii) non-conductive.

2. The semiconductor device of claim 1, further comprising a metal layer adjoining one of the first and second surfaces.

3. The semiconductor device of claim 1, wherein the trench structures contain a gaseous fluid.

4. The semiconductor device of claim 1, wherein the trench structures comprise or consist of one or more dielectric structures.

5. The semiconductor device of claim 1, wherein a maximum depth of the trench structures is less than a distance between the first surface and a planar interface between the one or more doped zones and the doped layer, the planar interface being parallel to the first surface.

6. The semiconductor device of claim 1, further comprising a plurality of doped zones.

7. The semiconductor device of claim 6, wherein the trench structures are formed between one of the doped zones and an extension portion of the doped layer, respectively, the extension portions adjoining the first surface and formed between the first surface and a contiguous portion of the doped layer, the contiguous portion and the doped zones forming at least in parts planar interfaces parallel to the first surface.

8. The semiconductor device of claim 7, wherein:

a distance between the at least in parts planar interface and the first surface is greater than a maximum depth of the trench structures; and

the doped zones comprise diffusion portions, each diffusion portion extending around a bottom portion of one of the trench structures, a distance between neighboring diffusion portions being narrower than a distance between trench structures assigned to an intermediate extension portion of the doped layer.

9. The semiconductor device of claim 1, wherein the recombination structure consists of or contains a metal or a conductive metal compound.

10. The semiconductor device of claim 1, wherein the recombination structure consists of or contains at least one of a material selected from a group containing amorphous semiconductor material, nanocrystalline semiconductor material, microcrystalline semiconductor material, polycrystalline semiconductor material and highly damaged monocrystalline semiconductor material.

11. The semiconductor device of claim 1, wherein the trench structures comprise a dielectric structure, respectively, each dielectric structure separating the corresponding recombination structure from the semiconductor body in a lateral direction parallel to the first surface.

12. The semiconductor device of claim 1, wherein the doped zone comprises a field stop portion arranged between a buried edge of the trench structures and the doped layer.

13. The semiconductor device of claim 12, wherein the field stop portion is a contiguous layer forming planar interfaces with the doped zones and the doped layer.

14. The semiconductor device of claim 12, wherein the field stop portion comprises segments aligned to the trench bottoms and separated from each other.

15. The semiconductor device of claim 12, wherein the field stop portion is separated from the doped zone.

16. The semiconductor device of claim 12, wherein the field stop portion has an extension along a direction vertical to the first surface that is larger than the carrier diffusion length in the field stop portion.

17. The semiconductor device of claim 12, wherein the field stop portion has an extension along a direction vertical to the first surface that is larger than three times the carrier diffusion length in the field stop portion.

18. The semiconductor device of claim 15, wherein the trench structures are formed between a doped zone and an extension portion of the doped layer, respectively, the extension portion adjoining the first surface and being formed between the first surface and a contiguous portion of the doped layer, the contiguous portion forming interfaces with the doped zones, the interfaces being parallel to the first surface.

19. The semiconductor device of claim 1, wherein the doped zone is formed in a cell area of the semiconductor body and is absent in an edge area surrounding the cell area, and the trench structures are formed in the cell area.

20. A semiconductor device comprising:

a semiconductor body comprising;

a doped layer of a first conductivity type; and

a doped zone of a second conductivity type opposite to the first conductivity type, wherein the doped zone is formed between the doped layer and a first surface of the semiconductor body; and

trench structures extending from one of the first and a second opposing surface into the semiconductor body, the trench structures comprising

a recombination structure at the bottom of each of one or more of the trench structures, the recombination structures directly adjoining the doped zone, the recombination structure exhibiting a surface recombination rate of at least 10⁴ cm/s at an interface to the doped zone, and

a fill structure separating the recombination structure from the first surface at least in a direction perpendicular to the first surface, the fill structure being either (i) conductive and not concurrently electrically connected to both the recombination and any other conductive structure outside the trench structure, or (ii) non-conductive.